Rattigan350: Customs are stupid. They are not logical.
Quite true. But very little that humans do is logical, since most of our behavior is managed by our subconscious, which operates by its own rules and doesn't care about logic. Our self-awareness and ability to reason allow us to override that programming on occasion, but we're still heavily dependent on our 'animal brain' for our behavior.
Religion is borne out of our need to form tight, us-versus-them social groups, but most of the cruft and nonsense around them are based on the attempts of primitive people to make sense of this behavior. None of it is logical, but every facet of it is explicitly human.